1. Field of the Invention
This invention relates in general to disk drives used for information storage in a computer, and more specifically to a device allowing electrostatic discharge of the slider within the disk drive.
2. Description of the Background Art
Disk drives using magnetic recording of digital information are used to store most of the information in contemporary computer systems. A disk drive typically has a housing with at least one rotatable magnetic disk having a plurality of concentric tracks of magnetically stored data. There is at least one recording head typically with a separate write element and read element for writing and reading data on the tracks. The recording head is constructed on a slider and the slider is attached to a suspension. The suspension is connected to an actuator which positions the recording head over a specific track of interest. The actuator first rotates to seek the track of interest and after positioning the recording head over that track maintains the recording head in close registration to that track.
The slider carrying the recording head has a disk facing surface upon which an air bearing is constructed. The purpose of the air bearing is to allow the slider to float on a cushion of air over the rotating disk and to be positioned close to the disk surface. Alternatively the disk facing surface of the slider may be designed to be in contact with the disk.
There is an advantage in designing the suspension to lift the slider away from the disk surface when the disk rotation is stopped. The disk surface may be very smooth thus enabling higher recording densities without the risk of encountering stiction between the slider and the disk. Accordingly some conventional disk drives have a plastic load/unload fixture having a base portion and a ramp portion attached to the disk drive housing. In addition, in these disk drives there is a tab on the suspension designed to engage the ramp portion of the load/unload fixture. In the prior art the entire load/unload fixture is formed from an insulating material.
To achieve very high recording density, the recording head must be very small. Unfortunately very small recording heads are subject to damage from electrostatic discharge. This is particularly true of the read element in the recording head. The smaller the read element, the greater the damage from a given amount of electrical discharge. Static electrical charge may accumulate on the slider from either van deGraff charging resulting from close proximity to the moving disk or tribological charging. In the past, partially conductive epoxy has been used to attach the slider to the metallic suspension. The resistance of the epoxy connection can vary substantially thus in some disk drives there is a residual amount of charge on the slider which can then discharge through the read element to the disk causing damage to the read element. Furthermore, the suspension usually does present an ideal conductive path to the housing because the electrical connection is through a bearing assembly which has only intermittent conduction. Thus, the discharge path between the slider and the disk drive housing is uncertain and indirect. The problem of electrical discharge causing damage to the read sensor is exacerbated with ever decreasing sizes of the read sensor.
From the foregoing it is apparent that an apparatus offering improved and safe static discharge of sliders is needed.
In a preferred embodiment, the invention provides for a conduction path directly from the slider to the housing of the disk drive.
In one embodiment, one or more conductive fibers are configured to provide an electrical discharge path between the slider and the disk drive housing. The conductive fibers can conveniently be permanently connected electrically to a conducting portion of the load/unload ramp which is connected to the housing and can be configured to touch the slider when it is unloaded from the disk surface. In an alternate embodiment a low force conductive cantilevered finger is permanently connected electrically to the housing and is used to touch the slider.
An embodiment of an electrical discharge device according to the present invention substantially reduces the risk of read element damage. Other aspects and advantages of the present invention will become apparent from the following detailed description which when taken in conjunction with the accompanying drawings illustrate by example the principles of the invention.